Formada3D Kratky hydroponic jar lids for mason and Fowlers Vacola jars: light-blocking, net-cup seat, fill port
A light-blocking lid that turns a preserving jar into a passive Kratky hydroponic planter for herbs and lettuce on the kitchen bench, with no pump. The lid sits on the jar rim with a 10 mm skirt (no thread, no seal), holds a net cup in a seat with a 10 mm guide collar, and on the larger sizes has a 6 mm fill and check port with a click plug, so you can top up or dip-check the solution without lifting the plant. Four sizes: wide-mouth mason (86 mm finish) and Fowlers Vacola size 3 take a 2 inch net cup; Fowlers size 4 takes a 3 inch cup; regular-mouth mason (70 mm) takes a 2 inch cup without a port. Black PETG, printed to order in our Melbourne workshop.
From A$8 for the 2 lids, mason regular mouth or Fowlers size 3. Printed to order in Melbourne and shipped Australia-wide; we confirm the final price and lead time before anything is printed.
On the quote page choose Request a quote (no file needed) and name this part and the option you want.
Order status. Mason lids use the published nominal finish sizes, and the loose 0.5 mm skirt absorbs brand variation. Fowlers Vacola publishes its jar sizes in inches only, so Fowlers lids come with a free rim coupon to set the exact size first.
What does it look like in use?
Renders are computer images of our own design, made from the same model we print. This family is made to order: real photos of our first prints are coming.
Specifications: material, size and what it fits
| Spec | Detail |
|---|---|
| Material | PETG (black, opaque so no algae grows in the cup area), 0.24 mm layers on a 0.6 mm nozzle, 4 walls, 15 % gyroid, no supports |
| Wide-mouth mason | Fits the 86 mm finish; 2 inch net-cup seat (51.6 mm, for cups made for a 51 mm hole) with fill port and plug. About 18 g |
| Regular-mouth mason | Fits the 70 mm finish; 2 inch net-cup seat, no port (no room inside the rim). About 12 g |
| Fowlers Vacola size 3 / size 4 | Size 3 (No. 14 / 20 / 27 jars): 2 inch cup seat, no port. Size 4 (No. 31 / 36 wide-neck jars): 3 inch cup seat (74.5 mm, for cups made for a 73-75 mm hole) with fill port and plug. About 16 g / 22 g |
| Fit | Skirt 0.5 mm per side over the rim (it only sits, no seal); plug 0.20 mm per side with a click ring. Mason finish sizes from published jar specifications; Fowlers sizes from the maker's accessory guide (inches only) |
| Not included | Jars, net cups, growing media, nutrients |
| Fit coupon | Free with an order for Fowlers sizes: three rim rings (78 / 80 / 82 mm for size 3, 102 / 104 / 106 mm for size 4). Drop them over your jar's rim and we print the lid to the one that sits flat |
Fowlers Vacola is a trademark of its owner, named only to describe the jar sizes these lids fit. These lids are our own design and are not affiliated with or endorsed by the jar maker.
How much does it cost?
Guide prices for printed parts, in Australian dollars. Shipping is extra; we confirm the final price, including any business minimum, before printing. Bulk and custom sizes are quoted per job.
| Option | From |
|---|---|
| 2 lids, regular-mouth mason | A$8 |
| 2 lids, Fowlers size 3 | A$8 |
| 2 lids with plugs, wide-mouth mason | A$8.95 |
| 2 lids with plugs, Fowlers size 4 | A$9.95 |
| Fowlers rim fit coupon | Free with an order |
Who it's for
Kitchen-bench herb and lettuce growers, gift buyers, schools teaching plant science, and anyone with a cupboard of preserving jars.
Safety & use
Installation & use. Designed for the uses described on this page only. Fixings are not included: use the sizes listed, check they are tight before use, and check the parts regularly for wear or damage. Not for safety-critical or overhead load-bearing use. Damage caused by misuse, modification or overloading isn't a fault in the product.
Water and food. PETG is not a certified food-contact material, and no printed part carries a food-safety certification. Indoor or shaded use; replace a part that turns cloudy, chalky or cracked. Rinse and clean with mild detergent or dilute hydrogen peroxide, not a dishwasher.
Glass. Use undamaged jars on a stable surface, and keep the plug and small parts away from young children.
This doesn't affect your rights under the Australian Consumer Law.
Common questions
What is Kratky hydroponics?
A passive method: the plant sits in a net cup above a jar of nutrient solution, the roots grow down into it, and as the level drops an air gap forms that the upper roots breathe from. No pump, no power. The lid holds the cup and keeps light off the solution.
Which jars do the lids fit?
Wide-mouth (86 mm finish) and regular-mouth (70 mm) mason jars, and Fowlers Vacola size 3 (No. 14, 20, 27) and size 4 (No. 31, 36) jars. The lid sits on the rim with a skirt; there is no thread.
Which net cups fit?
2 inch net cups made for a 51 mm hole in the mason and Fowlers size 3 lids, and 3 inch cups made for a 73-75 mm hole in the Fowlers size 4 lid. Cups are not included.
What is the port for?
On the wide-mouth and Fowlers size 4 lids, a 6 mm port with a click plug lets you top up the solution or dip-check it without lifting the plant out. The smaller lids have no room for it inside the rim.
How do I order?
Use Get a quote and choose Request a quote, naming the jar size and how many lids. We confirm the price and lead time before anything is printed.
More from the parts catalogue
Hydroponic tower kit for Australian 90 mm stormwater or 100 mm DWV PVC pipe: net-cup collars, top cap, base flange
Eight 45-degree net-cup collars, a rain-tray top cap and a bucket-lid flange that turn a plain AU PVC pipe and a 20 L bucket into a vertical tower.
NFT channel end caps, O-ring sealed, for 100 x 50 rectangular downpipe or 90 mm pipe (blank, low port or centre port)
Slip-over end caps for hydroponic NFT channels that seal with a standard 90 x 3.5 mm O-ring. Ports take a 1/2 inch BSP tank connector.
Drip irrigation manifold, 13 mm poly to 4 mm micro-tube, O-ring push-fit (4, 6 or 8 outlets)
A wall-mounted block that feeds up to 8 micro-tube drip lines from one 13 mm poly line, every tube sealed by its own O-ring.
Last updated 15 October 2026.